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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 17 Nov 2021.
AcrobatApplication · Adobe

CVE-2021-21017

HIGH · 8.8 CVSS v3.1 Published 2021-02-11
Fix available
A fix is available. Upgrade to after 20.013.20074 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild High EPSS Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Acrobat Reader DC versions versions 2020.013.20074 (and earlier), 2020.001.30018 (and earlier) and 2017.011.30188 (and earlier) are affected by a heap-based buffer overflow vulnerability. An unauthenticated attacker could leverage this vulnerability to achieve arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Heap-based buffer overflow vulnerability in Adobe Acrobat Reader DC allows an unauthenticated attacker to achieve arbitrary code execution via a malicious PDF file that the victim must open.

MitigationUpdate Adobe Acrobat Reader DC to a version later than 2020.013.20074, 2020.001.30018, or 2017.011.30188; avoid opening untrusted PDF files.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
AcrobatApplication
Affected:>= 17.0, <= 17.011.30188>= 20.0, <= 20.001.30018
Acrobat DcApplication
Affected:<= 20.013.20074
Acrobat ReaderApplication
Affected:>= 17.0, <= 17.011.30188>= 20.0, <= 20.001.300183
Acrobat Reader DcApplication
Affected:<= 20.013.20074

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check if Adobe Acrobat or Reader is installed
    On Windows, open Control Panel > Programs and Features, or run 'Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\* | Select-Object DisplayName, DisplayVersion' in PowerShell. On macOS, check /Applications folder for Adobe Acrobat or Adobe Reader.
    Affected if Adobe Acrobat or Adobe Acrobat Reader (either Classic or DC variant) appears in the installed programs list.
  2. Determine the exact installed version
    Open Adobe Acrobat/Reader, go to Help > About Adobe Acrobat Reader (or About Adobe Acrobat). The version number will display in the format like 20.xx.xxxx or 17.x.xxxx. Alternatively, on Windows, right-click the executable in Program Files and view Properties > Details.
  3. Compare version against affected ranges
    Match your installed version number to the affected ranges: Classic versions 17.0 through 17.011.30188 OR 20.0 through 20.001.30018/300183; DC versions up to and including 20.013.20074. For example, version 20.001.30018 is affected; version 20.013.20075 or later is not.
    Affected if The installed version falls within any of these ranges: 17.0 to 17.011.30188, 20.0 to 20.001.30018 (Acrobat), 20.0 to 20.001.300183 (Reader), or any DC version 20.013.20074 or lower.
  4. Verify the PDF handling component is in use
    Confirm that the application can open and render PDF files. This is the default behavior for both Acrobat and Reader installations.
    Affected if The application is capable of opening PDF files, which is the default configuration for both Acrobat and Reader.

You are affected if Adobe Acrobat or Acrobat Reader (Classic or DC) is installed and the version falls within 17.0-17.011.30188, 20.0-20.001.30018/300183, or DC versions up to 20.013.20074, and the application can open PDF files.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 20.013.20074
Interim mitigation

Update Adobe Acrobat Reader DC to a version later than 2020.013.20074, 2020.001.30018, or 2017.011.30188; avoid opening untrusted PDF files.

Recommended fix High confidence

Acrobat DC: 2020.013.20098+; Acrobat 2017: 2017.011.30193+; Acrobat 2020: 2020.001.30099+ (or latest current version)

  1. 1. Verify the current Adobe Acrobat or Acrobat Reader version by opening the application, selecting 'Help' > 'About Adobe Acrobat Reader' (or 'About Adobe Acrobat').
  2. 2. Identify which product line matches your installation: Standard/Pro (Acrobat), Acrobat DC (continuous track), or Acrobat Reader DC.
  3. 3. For Acrobat DC (continuous): Upgrade to version 2020.013.20098 or later.
  4. 4. For Acrobat 2017: Upgrade to version 2017.011.30193 or later.
  5. 5. For Acrobat 2020 (classic track): Upgrade to version 2020.001.30099 or later.
  6. 6. Download the updated version from the official Adobe website at get.adobe.com/reader or get.adobe.com/acrobat.
  7. 7. Close all Adobe applications before installing the update.
  8. 8. Run the installer and follow the prompts to complete the upgrade.
Caveat Standard upgrade with no expected breaking changes; Adobe updates are backward-compatible with existing PDF files and settings

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Acrobat Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,090
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,744.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-21017 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data